Start with getting the mirlitons going first, as they take a while to soften. In a large pot, place 3 pounds of whole mirlitons in and add enough water to cover by an inch. Bring it to a boil over high heat, then lower the heat just slightly so they stay at a low boil. Cook for 40-50 minutes, until they are fork tender.

Once done cooking, drain the water and set the mirlitons aside until cool enough to handle. When they are cool enough, this is how I prefer to prep them. Slice the mirlitons in half lengthwise, through the puckered part on top. Remove the seed and any harder areas around it, then use a peeler to remove the skin (optional). Chop the mirliton flesh into cubes and place them in a strainer set over a small pot to drain any excess water before using them.

While the mirlitons are boiling, start on the rest of your prep. In a small bowl, combine and mix 1 teaspoon salt, 1 teaspoon ground black pepper, 1 teaspoon smoked paprika, ½ teaspoon celery salt, ½ teaspoon garlic powder, ½ teaspoon onion powder, ½ teaspoon dried oregano, ½ teaspoon dried thyme, and ¼ teaspoon ground cayenne and set aside.

In a small skillet over medium-low heat, melt 1 tablespoon butter and add ¼ cup of panko. Cook, stirring frequently, until the panko starts to turn golden brown. When it starts to get some color, remove from the heat and transfer the panko to another dish to cool until needed.

Dice 1 yellow onion, 1 green bell pepper, and 1 celery rib roughly the same size and set aside. Mince 4-5 garlic cloves, finely chop ¼ cup fresh parsley, and chop 2 tablespoons green onion and set them aside as well.

Once the mirlitons are cooked, cooled, and chopped, you can begin working on the casserole. Preheat your oven to 350°F / 180°C. In a braising dish, large skillet, or Dutch-oven, melt the ¼ cup of butter over medium heat.

Add the diced yellow onion, green bell pepper, and rib of celery to the melted butter and sauté on medium to medium-high heat until the onions turn translucent, and the vegetables are softened, about 5-7 minutes.

When the vegetables are about done, add in 4-5 minced garlic cloves, ¼ cup finely chopped parsley, and 2 tablespoons chopped green onion. Stir to combine and cook for about another minute.

Once the garlic becomes fragrant, add in the chopped mirlitons and the remaining seasoning. Mix thoroughly and continue cooking, stirring occasionally. Using a fork or potato masher, mash up the mirliton as it cooks. They will release a lot of liquid as the flesh cooks, so continue cooking until a good amount of the water is released and cooked out, about 12-15 minutes longer.

After the mirlitons have been cooked and released most of their water, but before all the liquid evaporates, add 1 cup of Italian breadcrumbs. Add them in 2-3 additions, mixing thoroughly each time. The mixture should still be damp like a thick paste, but not so wet that it looks soupy. Add a bit more breadcrumbs if needed.

Once the casserole mixture is at the correct thickness, add the reserved shrimp. Fold the shrimp into the casserole until fully coated and let them cook for 2-3 minutes.

Remove the casserole from the heat and fold in the crawfish meat.

In a 13x9 baking dish or casserole dish, add the mirliton casserole mixture. Smooth out the top without compressing the mixture down too much. Now add the reserved toasted panko breadcrumbs on top in an even layer.

Place the baking dish in the middle of the oven, uncovered, and bake for 30 minutes.

Remove from the oven and allow to cool 5-10 minutes before serving.